With shrinking line-width and spacing, it has become increasingly challenging to minimize RC delays and crosstalk in interconnects, thereby requiring the use of ultra low k (ULK) dielectric materials (i.e., k2.5). This can introduce porous low k materials in copper interconnects, which is more susceptible to strip damage. An exemplary hardmask layer, such as titanium nitride (TiN) can provide high etch selectivity to low-k dielectrics and photoresist materials, works as anti-reflective film, and reduces ULK damage caused by photoresist ash strip processes. Unfortunately, the inventors have observed that existing hardmask layers, such as TiN hardmask layers, can have high compressive stress (1.6 GPa) that may result in line bending during ULK patterning.
Thus, the inventors have provided improved methods for depositing metal-containing layers that may be useful as hardmask layers using RF/DC PVD processes.